Convenient and accurate measurement of throat anatomy is relevant for daytime screening for obstructive sleep apnea (OSA). Obstructive sleep apnea is a medical condition wherein the upper respiratory tract is blocked by features within the oral cavity of throat of the patient, preventing a patient from breathing normally, especially when sleeping.
Today, patients exhibiting OSA symptoms need to be monitored during their sleep, and need to go to a sleep lab. This is very tedious and labour-intensive. Obviously, more comfortable and less time-consuming approaches are needed.
Alternative practices which may indicate the presence of OSA with a patient, without sleep lab, are still not accurate enough and cannot sufficiently be trusted. Visual methods include classifying the ensemble of oral cavity and throat in categories (e.g. by using Mallampati scores, see FIG. 1(a), or tonsil grade scores, see FIG. 1(b)) by visual inspection by a human expert. Obviously this implies subjective interpretation and low reproducibility. A follow-up in time of the specific patient's evolution is difficult, and different human experts may categorise the same patient differently.
Another alterative practice comprises the use of a pharyngometer, which is based on an acoustic scanning of the nasal or oral cavity. A good acoustic seal is required for an accurate measurement, which is difficult to achieve. Acoustic scanning provides only little information on the anatomy. Advanced 3D imaging techniques as for instance MRI are expensive and are only available in hospitals, whereas OSA screening typically takes place in the office a primary health physician.
A camera has been used to measure craniofacial anatomic features related to OSA, in “Craniofacial Phenotyping in Obstructive Sleep Apnea—A Novel Quantitative Photographic Approach”, Richard W. W. Lee et al., published in SLEEP, Vol. 32, No. 1, 2009. Parameters relating to craniofacial morphology are derived from frontal-profile photographs of patients.